fix: do not build polled image URLs before the SDK is initialized

inc/rest.php

@@ -706,6 +706,11 @@ public function disconnect( WP_REST_Request $request ) {
 	 * @return WP_REST_Response
 	 */
 	public function poll_optimized_images( WP_REST_Request $request ) {
+		// The image URLs are built with the Optimole SDK, which is only initialized for a connected site.
+		if ( ! ( new Optml_Settings() )->is_connected() ) {
+			return $this->response( [] );
+		}
+
 		$api_key = $request->get_param( 'api_key' );
 		$request = new Optml_Api();
 		$images  = $request->get_optimized_images( $api_key );

tests/test-poll-optimized-images.php

@@ -182,6 +182,49 @@ public function test_poll_returns_empty_list_when_list_empty() {
 		$this->assertSame( [], $payload['data'] );
 	}
 
+	/**
+	 * Without a connection the SDK is not initialized, so a list cannot be turned into image URLs:
+	 * polling returns an empty list instead of throwing, and does not call the API.
+	 */
+	public function test_poll_returns_empty_list_when_not_connected(): void {
+		( new Optml_Settings() )->update( 'service_data', [] );
+		$requests = 0;
+
+		/**
+		 * An API response with one image, counting the requests.
+		 *
+		 * @return array{headers: array<string, string>, body: string, response: array{code: int, message: string}}
+		 */
+		$this->http_mock = function () use ( &$requests ): array {
+			++$requests;
+			return [
+				'headers'  => [],
+				'body'     => wp_json_encode(
+					[
+						'code' => 200,
+						'data' => [
+							'list' => [
+								[
+									'url' => 'https://example.com/photo.jpg',
+									'key' => 'AbC',
+								],
+							],
+						],
+					]
+				),
+				'response' => [
+					'code'    => 200,
+					'message' => 'OK',
+				],
+			];
+		};
+
+		$payload = $this->poll();
+		$this->assertSame( 'success', $payload['code'] );
+		$this->assertSame( [], $payload['data'] );
+		$this->assertSame( 0, $requests );
+	}
+
 	/**
 	 * A valid list is returned (URLs rewritten through Optimole).
 	 */